The present invention is in the field of optics, specifically in integrated optics bends, splitters, and resonators. High index contrast waveguides provide high-density integration for optical networking and on-chip optical interconnects. One of the main features of high index contrast waveguides has been the demonstrated ability to manufacture low loss compact bends, splitters and resonators.
It is has been shown that the bending loss for a 1 μm radius of curvature bend in a silicon high index contrast strip waveguide is 0.5 dB/turn. However, this number is still much larger than the theoretically predicted bending loss. Furthermore, a splitting loss of 0.2 dB has been reported with a Y-split angle of 2 degrees. This small split angle results in a rather long, 30 micron, Y-splitter.
To address this problem, the article C. Manotalou et al., “High-Density Integrated Optics”, Journal of Lightwave Technology, 1999, vol. 17, no. 9, proposed two dimensional bends and splitters based on a two-dimensional high transmission cavity (HTC) with a polygonal shape. High transmissions cavity bends and splitters were designed with bandwidths exceeding 100 nm and transmission rates greater than 95%.
The two dimensional high transmission cavities (HTCs) are shaped as polygons, with one side at a 45 degree angle to the incoming and outgoing waveguides. A 2-D HTC bend may be formed by adding two waveguides together, thus forming two coupled resonators.
There was a need in the art to provide a way to split incoming optical signals in a waveguide into two separate and distinct signals. Specifically, 2-D HTC Y-splits were important because they accomplished that task of splitting an incoming signal into two separate signals. The geometry of the 2-D Y-split HTC was such that the splitting point was 90 degrees and the splitting area was small. The 2-D Y-splitter HTC did this most efficiently, because the two splitted signals were directed away from each other.